Method and apparatus for changing a deployed position for a tail skid assembly

ABSTRACT

A method and apparatus for positioning a tail skid assembly for a maximum rotation angle for an aircraft may be provided. A determination may be made as to whether the tail skid assembly is to be deployed for takeoff or landing. A set of parameters may be identified based on a determination of whether the tail skid assembly is to be deployed for takeoff or landing. A desired maximum rotation angle for the aircraft may be identified using the set of parameters. The tail skid assembly may be deployed to allow the desired maximum rotation angle for the aircraft.

This application is a divisional of U.S. patent application Ser. No.13/416,914, filed Mar. 9, 2012, which is incorporated by referenceherein in its entirety.

BACKGROUND INFORMATION

1. Field

The present disclosure relates generally to aircraft rotation duringtakeoff and landing and, in particular, to a method and apparatus forchanging a maximum rotation angle for an aircraft during takeoff andlanding.

2. Background

Rotation of an aircraft about a pitch axis through the aircraft duringtakeoff or landing may cause a tail section of the aircraft to come intocontact with a surface from which the aircraft is taking off or asurface on which the aircraft is landing. A tail skid assembly attachedto the underside of the tail section of an aircraft may be used tosubstantially prevent the tail section of the aircraft from coming intocontact with a surface from which the aircraft is taking off or asurface on which the aircraft is landing.

In this manner, the surface may come into contact with the tail skidassembly before coming into contact with the underside of the tailsection of the aircraft. Further, the tail skid assembly may comprise ashock absorber that absorbs and/or dissipates the energy generated inresponse to contact between the end of the tail skid assembly and thesurface.

The maximum angle at which the aircraft may rotate about the pitch axisbefore the tail skid assembly comes into contact with the surface may bereferred to as a “maximum rotation angle” for the aircraft. The maximumrotation angle desired for an aircraft during takeoff may be differentfrom the maximum rotation angle desired for the aircraft during landing.

The maximum rotation angle desired at takeoff and landing may bedetermined based on the amount of energy generated when the tail skidassembly comes into contact with the surface, the amount of energy thatcan be absorbed and/or dissipated by the shock absorber in the tail skidassembly, a length of the aircraft, a distance between an end of thetail skid assembly and the bottom of a tail section of the aircraft,and/or other types of factors. Other factors may include, for example,without limitation, a change in the weight of the aircraft betweentakeoff and landing, reduced fuel weight due to fuel consumption,landing speed, takeoff speed, takeoff and/or landing requirementsspecific to a particular airport, landing field length (LFL), andtakeoff field length (TOFL).

For example, an aircraft may have a lower weight at the time of landingas compared to the weight of the aircraft at the time of takeoff. Thisreduction in weight may be the result of, for example, withoutlimitation, fuel consumption during flight, the dropping of cargo duringflight, and/or other suitable factors.

With this reduced weight for the aircraft, the energy generated when anend of a tail skid assembly for the aircraft contacts the surface onwhich the aircraft is landing may be less than the energy generatedduring takeoff when the aircraft does not have the reduced weight. Thelower energy generated during landing may allow the aircraft to have agreater maximum rotation angle during landing as compared to takeoff.

Additionally, an aircraft may have different ground clearancerequirements when taking off as compared to landing. As used herein, the“ground clearance” for an aircraft may be the distance between theundermost portion of a tail skid assembly for the aircraft that isconfigured to come into contact with a surface and an underside of thetail section of the aircraft. The ground clearance needed by an aircraftduring landing may be less than the ground clearance needed duringtakeoff.

Further, a lower ground clearance may allow the speed of the aircraft tobe reduced to a desired speed during landing as compared to a greaterground clearance. A lower ground clearance may allow a greater maximumrotation angle for the aircraft as compared to a greater groundclearance.

With some currently available aircraft, the maximum rotation angle forthe aircraft may not be adjusted between takeoff and landing. Therefore,it would be desirable to have a method and apparatus that takes intoaccount at least some of the issues discussed above as well as possiblyother issues.

SUMMARY

In one illustrative example, a tail skid assembly may comprise anelongate structure and a deployment device. The elongate structure maybe connected to a tail section of an aircraft. The deployment device maybe connected to the elongate structure. The deployment device may beconfigured to move such that a deployed position for the elongatestructure changes to one of a plurality of deployed positions for theelongate structure.

In another illustrative example, a tail skid assembly may comprise anelongate structure and a deployment device. The elongate structure mayhave a first end and a second end. The first end may be connected to atail section of an aircraft. The deployment device may be connected tothe elongate structure. The deployment device may be configured to movesuch that a distance between the second end of the elongate structureand a bottom of the tail section of the aircraft changes to one of aplurality of selected distances.

In yet another illustrative example, a method for positioning a tailskid assembly for a maximum rotation angle for an aircraft may beprovided. A determination may be made as to whether the tail skidassembly is to be deployed for takeoff or landing. A set of parametersmay be identified based on the determination of whether the tail skidassembly is to be deployed for takeoff or landing. A desired maximumrotation angle for the aircraft may be identified using the set ofparameters. The tail skid assembly may be deployed to allow the desiredmaximum rotation angle.

In still yet another illustrative example, a method for positioning atail skid assembly for a maximum rotation angle for an aircraft may beprovided. A determination may be made as to whether the tail skidassembly is to be deployed for takeoff or landing. A set of parametersmay be identified based on a determination of whether the tail skidassembly is to be deployed for takeoff or landing. A desired maximumrotation angle for the aircraft may be identified using the set ofparameters. A deployment device in the tail skid assembly may be movedto change a deployed position for an elongate structure in the tail skidassembly. The elongate structure may have a first end and a second endin which the first end is connected to a tail section of the aircraft.Changing the deployed position for the elongate structure may change adistance between the second end of the elongate structure and a bottomof the tail section of the aircraft to allow the desired maximumrotation angle for the aircraft.

The features and functions can be achieved independently in variousembodiments of the present disclosure or may be combined in yet otherembodiments in which further details can be seen with reference to thefollowing description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the illustrativeembodiments are set forth in the appended claims. The illustrativeembodiments, however, as well as a preferred mode of use, furtherobjectives, and features thereof will best be understood by reference tothe following detailed description of an illustrative embodiment of thepresent disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of a block diagram of a tail skid assembly foran aircraft in the form of a block diagram in accordance with anillustrative embodiment;

FIG. 2 is an illustration of a tail skid assembly for an aircraft inaccordance with an illustrative embodiment;

FIG. 3 is an illustration of a perspective view of a tail skid assemblyin accordance with an illustrative embodiment;

FIG. 4 is an illustration of a perspective view of a tail skid assemblyin accordance with an illustrative embodiment;

FIG. 5 is an illustration of a cross-sectional side view of a tail skidassembly in accordance with an illustrative embodiment;

FIG. 6 is an illustration of a cross-sectional side view of a tail skidassembly in accordance with an illustrative embodiment;

FIG. 7 is an illustration of an end view of a tail skid assembly inaccordance with an illustrative embodiment;

FIG. 8 is an illustration of an end view of a tail skid assembly inaccordance with an illustrative embodiment;

FIG. 9 is an illustration of an isometric view of a cam for a tail skidassembly in accordance with an illustrative embodiment;

FIG. 10 is an illustration of a side view of an aircraft with a tailskid assembly in contact with a surface in accordance with anillustrative embodiment;

FIG. 11 is an illustration of an enlarged side view of a tail skidassembly in contact with a surface in accordance with an illustrativeembodiment;

FIG. 12 is an illustration of a side view of an aircraft with a tailskid assembly in contact with a surface in accordance with anillustrative embodiment;

FIG. 13 is an illustration of an enlarged side view of a tail skidassembly in contact with a surface in accordance with an illustrativeembodiment;

FIG. 14 is an illustration of a flowchart of a process for positioning atail skid assembly for a maximum rotation angle for an aircraft in theform of a flowchart in accordance with an illustrative embodiment;

FIG. 15 is an illustration of an aircraft manufacturing and servicemethod in accordance with an illustrative embodiment; and

FIG. 16 is an illustration of an aircraft in which an illustrativeembodiment may be implemented.

DETAILED DESCRIPTION

The different illustrative embodiments recognize and take into accountdifferent considerations. For example, the different illustrativeembodiments recognize and take into account that a tail skid assemblythat allows an aircraft to have a maximum rotation angle during landingthat is greater than a maximum rotation angle during takeoff may bedesirable. Further, the different illustrative embodiments recognize andtake into account that a tail skid assembly that does not add undesiredweight, undesired complexity, undesired load paths, and/or increasedmaintenance costs to the aircraft may be desirable.

Thus, the different illustrative embodiments provide a method andapparatus for changing a deployed position for an elongate structure ina tail skid assembly for an aircraft between takeoff and landing. In oneillustrative example, a tail skid assembly may comprise an elongatestructure and a deployment device. The elongate structure may beconnected to a tail section of an aircraft. The deployment device may beconnected to the elongate structure. The deployment device may beconfigured to move such that a deployed position for the elongatestructure changes to one of a plurality of deployed positions for theelongate structure.

With reference now to the figures and, in particular, with reference toFIG. 1, an illustration of a tail skid assembly for an aircraft in theform of a block diagram is depicted in accordance with an illustrativeembodiment. As depicted, aircraft 100 may have body 102 with tailsection 104.

In these illustrative examples, tail skid assembly 106 may be connectedto tail section 104. As used herein, when one component may be“connected” to another component, this connection is a physicalassociation. For example, a first component, such as tail skid assembly106, may be considered to be connected to a second component, such astail section 104 of aircraft 100, by being secured to the secondcomponent, bonded to the second component, mounted to the secondcomponent, welded to the second component, fastened to the secondcomponent, and/or connected to the second component in some othersuitable manner.

Further, the first component may be directly or indirectly connected tothe second component. In other words, additional components may bepresent between the first component and the second component. The firstcomponent may be considered to be indirectly connected to the secondcomponent when one or more additional components are present between thetwo components. When the first component is directly connected to thesecond component, no additional components may be present between thetwo components. In some cases, the first component may also be connectedto the second component by being formed as part of and/or as anextension of the second component.

Tail skid assembly 106 may be configured to substantially prevent tailsection 104 of aircraft 100 from contacting surface 108 during at leastone of takeoff 110, landing 112, and some other suitable phase of flightfor aircraft 100. Surface 108 may be any surface on which aircraft 100may perform landing 112 or from which aircraft 100 may perform takeoff110. For example, without limitation, surface 108 may be the surface ofa runway, a grassy surface, a concrete surface, a snow-covered surface,a surface onboard a ship, or some other suitable type of surface.

In these illustrative examples, tail skid assembly 106 may compriseshock absorber 114, elongate structure 113, contact member 117,deployment device 119, actuator system 120, and elongate member 122.Shock absorber 114 may be any device configured to absorb and/ordissipate energy 115 resulting from impact. In particular, shockabsorber 114 may be configured to smooth out shock resulting from impactand dissipate energy 115. Energy 115 may comprise kinetic energy inthese examples.

Further, in these illustrative examples, elongate structure 113 may takethe form of lever 116. In some cases, lever 116 may be considered a“tail skid” for tail skid assembly 106. Additionally, deployment device119 may take the form of cam 118 in these examples.

Shock absorber 114 and lever 116 may be connected to tail section 104 ofaircraft 100. In one illustrative example, lever 116 and shock absorber114 may each be connected to structure 124 in tail section 104 ofaircraft 100. Structure 124 may take the form of, for example, withoutlimitation, a structural panel, an intercostal, a mechanical device, orsome other suitable type of structure.

As depicted, lever 116 may have first end 126 and second end 128. Firstend 126 may be connected to structure 124 in tail section 104 ofaircraft 100 at connection 130. As used herein, a “connection”, such asconnection 130, may comprise any number of fasteners, pins, hinges,openings, and/or other suitable components for connecting a firstcomponent, such as lever 116, to a second component, such as structure124.

Further, a “connection” between a first component and a secondcomponent, as used herein, may allow the first component and/or thesecond component to rotate about an axis through the connection. Forexample, second end 128 of lever 116 may rotate about axis 132 throughconnection 130. Axis 132 may be a fixed axis of rotation in theseillustrative examples.

Additionally, contact member 117 may be associated with second end 128of lever 116 in these illustrative examples. As used herein, when onecomponent is “associated” with another component, this association maybe a physical association. For example, a first component, such ascontact member 117, may be considered to be associated with a secondcomponent, such as lever 116, by being secured to the second component,bonded to the second component, mounted to the second component, weldedto the second component, fastened to the second component, and/orconnected to the second component in some other suitable manner. Thefirst component also may be connected to the second component using athird component. The first component may also be considered to beassociated with the second component by being formed as part of and/oran extension of the second component.

In one illustrative example, contact member 117 may be a separatecomponent configured for attachment to second end 128 of lever 116. Ofcourse, in other illustrative examples, contact member 117 may be partof lever 116. Contact member 117 may be configured for contact withsurface 108. In particular, contact member 117 may come into contactwith surface 108 prior to the underside of tail section 104 contactingsurface 108.

Contact member 117 may take various forms. In these depicted examples,contact member 117 may take the form of a “shoe”. However, in otherillustrative examples, contact member 117 may take the form of, forexample, without limitation, a cover, a roller, a skid plate, a cap, orsome other suitable type of member selected for contact with surface108. Contact member 117 may be removable and replaceable in theseillustrative examples.

Cam 118 may be connected to shock absorber 114 at connection 134. Morespecifically, cam 118 may be rotatably connected to shock absorber 114at connection 134 such that cam 118 may rotate about axis 136 throughconnection 134.

Further, cam 118 may also be connected to lever 116. Cam 118 may belocated between shock absorber 114 and lever 116 in these examples. Inone illustrative example, pin 138 may be used to connect cam 118 tolever 116. For example, without limitation, pin 138 may be insertedthrough opening 140 in cam 118 and into elongate opening 142 in lever116.

Pin 138, with cam 118 connected to pin 138, may be moved in asubstantially linear direction through elongate opening 142 by actuatorsystem 120. Actuator system 120 may attach to pin 138. In this manner,actuator system 120 may be indirectly connected to cam 118. Movement ofpin 138 by actuator system 120 causes cam 118 to move. Actuator system120 also may be connected to lever 116 in these examples.

Actuator system 120 may comprise one or more actuators. In theseillustrative examples, actuator system 120 may take the form of ahydraulic actuator configured to move pin 138 through elongate opening142 in a substantially linear direction. Of course, in otherillustrative examples, actuator system 120 may comprise at least one ofa hydraulic actuator, a linear actuator, a pneumatic actuator, and someother suitable type of actuator.

Elongate member 122 may be connected to actuator system 120 atconnection 144. Elongate member 122 may be configured to rotate aboutaxis 146 through connection 144. Further, elongate member 122 may beconnected to cam 118 at connection 148. Cam 118 may be configured torotate about axis 150 through connection 148.

In these illustrative examples, elongate member 122 may have a fixedlength and may remain substantially rigid when actuator system 120 isoperated. Elongate member 122 may take the form of, for example, withoutlimitation, a rod, a reaction link, a support beam, or some othersuitable type of elongate member.

When actuator system 120 is operated to move pin 138 through elongateopening 142, elongate member 122 connected to both actuator system 120and cam 118 may create moment 152. Moment 152 may cause cam 118 torotate about axis 136 through connection 134 between shock absorber 114and cam 118. In particular, moment 152 may cause cam 118 to rotate aboutaxis 136 through connection 134 without rotating shock absorber 114outside of selected tolerances.

As depicted, cam 118 may have eccentric geometry 145. In other words,cam 118 may have first length 147 that is different from second length149 for cam 118. In these illustrative examples, first length 147 andsecond length 149 may each intersect axis 136 through connection 134. Insome cases, first length 147 and second length 149 may be substantiallyorthogonal to each other.

Rotation of cam 118 having eccentric geometry 145 about axis 136 throughconnection 134 may change a position of lever 116 relative to connection134. In particular, rotation of cam 118 may change position 154 ofsecond end 128 of lever 116 relative to connection 134. For example,without limitation, rotation of cam 118 may move second end 128 of lever116 closer to or further away from connection 134.

Changing position 154 of second end 128 of lever 116 may change maximumrotation angle 156 for aircraft 100. In these illustrative examples,maximum rotation angle 156 may be the maximum angle at which aircraft100 may be rotated about pitch axis 158 before contact member 117 atsecond end 128 of lever 116 comes into contact with surface 108 duringtakeoff 110 or landing 112. First length 147 and second length 149 maybe selected such that maximum rotation angle 156 may be changed betweentakeoff 110 and landing 112 by a desired amount.

Cam 118 may be rotated such that a deployed position for lever 116changes to one of a plurality of deployed positions for lever 116. Inthis manner, lever 116 may have two or more possible deployed positionswhen tail skid assembly 106 is deployed.

As one illustrative example, cam 118 may be rotated to one of firstposition 160 relative to lever 116 and second position 162 relative tolever 116. First position 160 may be for takeoff 110, and secondposition 162 may be for landing 112. Cam 118 may be rotated to firstposition 160 such that lever 116 has a first deployed position. Cam 118may be rotated to second position 162 such that lever 116 has a seconddeployed position.

In these illustrative examples, when lever 116 has the first deployedposition, tail skid assembly 106 may be considered as having a firstdeployed position. Further, when lever 116 has the second deployedposition, tail skid assembly 106 may be considered as having a seconddeployed position. In this manner, changing a deployed position forlever 116 may be considered changing a deployed position for tail skidassembly 106.

Further, in these depicted examples, rotation of cam 118 changes adistance between second end 128 of lever 116 and a bottom of tailsection 104 of aircraft 100 to one of a plurality of selected distances.Each selected distance in this plurality of selected distances may beselected to provide a different maximum rotation angle for aircraft 100when tail skid assembly 106 is deployed. As the distance between secondend 128 of lever 116 and the bottom of tail section 104 of aircraft 100decreases, the maximum rotation angle allowed for aircraft 100increases.

For example, without limitation, when lever 116 has the first deployedposition, contact member 117 at second end 128 of lever 116 may have afirst distance from tail section 104 of aircraft 100. When lever 116 hasthe second deployed position, contact member 117 may have a seconddistance from tail section 104 of aircraft 100. The first distancebetween contact member 117 and tail section 104 may be greater than thesecond distance between contact member 117 and tail section 104.Rotating cam 118 between first position 160 and second position 162 maychange maximum rotation angle 156 for aircraft 100.

When cam 118 is in first position 160, aircraft 100 may have firstmaximum rotation angle 164 for takeoff 110. When cam 118 is in secondposition 162, aircraft 100 may have second maximum rotation angle 166for landing 112.

Second maximum rotation angle 166 may be greater than first maximumrotation angle 164 in this illustrative example. For example, withoutlimitation, second maximum rotation angle 166 may be greater than firstmaximum rotation angle 164 by about one degree.

Consequently, when cam 118 is rotated to second position 162 for landing112, aircraft 100 may be rotated about pitch axis 158 to a greaterdegree before contact member 117 contacts surface 108 as compared towhen cam 118 is rotated to first position 160. A smaller distancebetween contact member 117 and tail section 104 of aircraft 100 mayallow a greater maximum rotation angle for aircraft 100 as compared to agreater distance between contact member 117 and tail section 104 ofaircraft 100.

In this manner, the different illustrative embodiments provide tail skidassembly 106 configured to change maximum rotation angle 156 foraircraft 100 between takeoff 110 and landing 112. Further, the differentillustrative embodiments may provide an apparatus for changing maximumrotation angle 156 that does not increase the weight and/or cost ofaircraft 100 more than desired.

The illustration of tail skid assembly 106 in aircraft 100 in FIG. 1 isnot meant to imply physical or architectural limitations to the mannerin which an illustrative embodiment may be implemented. Other componentsin addition to or in place of the ones illustrated may be used. Somecomponents may be unnecessary. Also, the blocks may be presented toillustrate some functional components. One or more of these blocks maybe combined, divided, or combined and divided into different blocks whenimplemented in an illustrative embodiment.

For example, although deployment device 119 has been described as cam118, deployment device 119 may take other forms. In some illustrativeexamples, deployment device 119 may take the form of a planar member, anelectromechanical device, a structure comprising one or more components,or some other suitable type of structure or device configured to berotated by operation of actuator system 120 and configured to change adeployed position for elongate structure 113 when rotated.

Further, elongate structure 113 may take some form other than lever 116.For example, without limitation, elongate structure 113 may be a rod, abeam, a tube, an electromechanical device, or some other suitable typeof elongate structure.

With reference now to FIGS. 2-13, illustrations of a tail skid assemblyfor an aircraft are depicted in accordance with an illustrativeembodiment. In FIGS. 2-13, an example of one implementation for a tailskid assembly for an aircraft may be depicted. The tail skid assemblydescribed in FIGS. 2-13 may be an example of one implementation for tailskid assembly 106 for aircraft 100 in FIG. 1.

With reference now to FIG. 2, an illustration of an aircraft is depictedin accordance with an illustrative embodiment. In this illustrativeexample, aircraft 200 may have wing 202 and wing 204 attached tofuselage 206. Further, aircraft 200 may include engine 208 attached towing 202 and engine 210 attached to wing 204.

Fuselage 206 may have nose section 211 and tail section 212. Horizontalstabilizer 214, horizontal stabilizer 216, and vertical stabilizer 218may be attached to tail section 212 of fuselage 206. Further, tail skidassembly 220 may be attached to underside 222 of tail section 212 offuselage 206. Tail skid assembly 220 may be an example of oneimplementation for a tail skid assembly in accordance with the differentillustrative embodiments.

Tail skid assembly 220 may be configured to substantially prevent tailsection 212 of aircraft 200 from contacting a surface (not shown) whenaircraft 200 rotates about pitch axis 224. For example, withoutlimitation, aircraft 200 may rotate about pitch axis 224 when aircraft200 takes off and lands. In particular, aircraft 200 may rotate in thedirection of arrow 226 about pitch axis 224 during takeoff and landing.

When aircraft 200 rotates about pitch axis 224 in the direction of arrow226, nose section 211 of aircraft 200 may be moved upwards, while tailsection 212 of aircraft 200 may be moved downwards. During takeoff, tailsection 212 may be moved closer to the surface from which aircraft 200is taking off. During landing, tail section 212 may be moved closer tothe surface on which aircraft 200 is landing. Tail skid assembly 220 maybe used to substantially prevent tail section 212 from contacting thesesurfaces during takeoff and landing.

Turning now to FIG. 3, an illustration of a perspective view of tailskid assembly 220 is depicted in accordance with an illustrativeembodiment. In this illustrative example, tail skid assembly 220 isconnected to structure 301. Structure 301 may be a structure in tailsection 212 in FIG. 2. In particular, structure 301 may be anintercostal in this depicted example.

Tail skid assembly 220 may include shock absorber 302, lever 304,contact member 306, cam 308, actuator system 310, and elongate member312. As depicted, shock absorber 302 and lever 304 may be connected tostructure 301.

Lever 304 may have first end 314 and second end 316. First end 314 maybe rotatably connected to structure 301 at connection 318. As depicted,connection 318 may include pin 320 inserted through opening 322 ofstructure 301 and opening 324 at first end 314 of lever 304. Second end316 of lever 304 may be configured to rotate about axis 326 throughconnection 318 in the direction of arrow 327. Further, contact member306 may be attached to second end 316 of lever 304. In this illustrativeexample, contact member 306 may be referred to as a “shoe”.

Additionally, cam 308 may be rotatably connected to shock absorber 302at connection 328. Connection 328 may include pin 330 inserted throughopening 332 in shock absorber 302 and opening 334 in cam 308. Cam 308may rotate about axis 336 through connection 328 in the direction ofarrow 337.

Further, cam 308 may also be connected to lever 304. Pin 338 may connectcam 308 to lever 304. As depicted, pin 338 may extend through opening340 in cam 308 and into elongate opening 342 in lever 304.

In this illustrative example, actuator system 310 may be connected topin 338. Actuator system 310 may be hydraulic actuator 344 in thisdepicted example. Operation of actuator system 310 may cause pin 338 tomove in the direction of arrow 346. In other words, actuator system 310may move pin 338 in a substantially linear direction along arrow 346.

Elongate member 312 may be connected to actuator system 310 atconnection 348. Connection 348 may include pin 350 inserted throughopening 352 of elongate member 312 and opening 354 in actuator system310. Elongate member 312 may be rotated about axis 356 throughconnection 348 in the direction of arrow 357. In this illustrativeexample, elongate member 312 may be referred to as a “reaction link”.

Elongate member 312 may also be connected to cam 308 at connection 358.Connection 358 may include pin 360 inserted through opening 362 of cam308. In particular, elongate member 312 may be attached to pin 360. Whenactuator system 310 moves pin 338 through elongate opening 342 in thedirection of arrow 347, the attachment between elongate member 312 andpin 360 in cam 308 may create moment 364.

Moment 364 may cause cam 308 to rotate about axis 336 through connection328. Rotation of cam 308 about axis 336 may, in turn, cause a positionof second end 316 of lever 304 to be changed. As depicted, cam 308 maybe rotated to first position 366 relative to lever 304 for takeoff. Infirst position 366, second end 316 of lever 304 may be in a positionthat provides a desired maximum rotation angle for takeoff.

With reference now to FIG. 4, an illustration of a perspective view oftail skid assembly 220 is depicted in accordance with an illustrativeembodiment. In this illustrative example, actuator system 310 may movepin 338 such that cam 308 may be rotated about axis 336 throughconnection 328. As depicted, cam 308 may be rotated to second position400 relative to lever 304 for landing.

In second position 400, second end 316 of lever 304 may be in a positionthat provides a desired maximum rotation angle for landing. The maximumrotation angle provided when cam 308 is in second position 400 may begreater than the maximum rotation angle provided when cam 308 is infirst position 366 in FIG. 3.

With reference now to FIG. 5, an illustration of a cross-sectional sideview of tail skid assembly 220 is depicted in accordance with anillustrative embodiment. As depicted, a cross-sectional side view oftail skid assembly 220 taken along lines 5-5 in FIG. 3 is seen in FIG.5. Cam 308 may be in first position 366 for takeoff in this depictedexample. This cross-sectional view may allow actuator system 310connected to pin 338 and elongate member 312 connected to pin 360 atconnection 358 to be seen more clearly.

With reference now to FIG. 6, an illustration of a cross-sectional sideview of tail skid assembly 220 is depicted in accordance with anillustrative embodiment. As depicted, a cross-sectional side view oftail skid assembly 220 taken along lines 6-6 in FIG. 4 is seen in FIG.6. Cam 308 may be in second position 400 for landing in this depictedexample. This cross-sectional view may allow actuator system 310connected to pin 338 and elongate member 312 connected to pin 360 atconnection 358 to be seen more clearly.

With reference now to FIG. 7, an illustration of an end view of tailskid assembly 220 is depicted in accordance with an illustrativeembodiment. In FIG. 7, an end view of tail skid assembly 220 with cam308 in first position 366 for takeoff may be depicted taken with respectto lines 7-7 in FIG. 3.

In this illustrative example, distance 700 may be the distance betweenbottom 702 of contact member 306 and axis 336 through connection 328.Bottom 702 of contact member 306 may be the undermost portion of cam308. In this manner, distance 700 may be an indication of the groundclearance provided by tail skid assembly 220 during takeoff.

With reference now to FIG. 8, an illustration of an end view of tailskid assembly 220 is depicted in accordance with an illustrativeembodiment. In FIG. 8, an end view of tail skid assembly 220 with cam308 in second position 400 for landing may be depicted taken withrespect to lines 8-8 in FIG. 4.

In this illustrative example, distance 800 may be the distance betweenbottom 702 of contact member 306 and axis 336 through connection 328.Distance 800 may be an indication of the ground clearance provided bytail skid assembly 220 during landing. In this illustrative example,distance 700 in FIG. 7 may be greater than distance 800 in FIG. 8. Inthis manner, tail skid assembly 220 may provide a greater groundclearance during takeoff than during landing.

With reference now to FIG. 9, an illustration of an isometric view ofcam 308 for tail skid assembly 220 in FIGS. 2-8 is depicted inaccordance with an illustrative embodiment. In this illustrativeexample, cam 308 may be depicted without any of the other components fortail skid assembly 220 to allow cam 308 to be more clearly seen. Inparticular, opening 334, opening 340, and opening 362 in cam 308 may bemore clearly seen.

With reference now to FIG. 10, an illustration of a side view ofaircraft 200 with tail skid assembly 220 in contact with a surface isdepicted in accordance with an illustrative embodiment. In thisillustrative example, aircraft 200 may be rotated about pitch axis 224in FIG. 2 during takeoff from surface 1000.

Surface 1000 may be, for example, without limitation, the ground on arunway. During takeoff from surface 1000, tail skid assembly 220 maycome into contact with surface 1000 to substantially prevent tailsection 212 of aircraft 200 from contacting surface 1000.

Turning now to FIG. 11, an illustration of an enlarged side view of tailskid assembly 220 in contact with surface 1000 is depicted in accordancewith an illustrative embodiment. In FIG. 11, an enlarged side view oftail skid assembly 220 in contact with surface 1000 during takeoff inFIG. 10 may be depicted taken with respect to lines 11-11 in FIG. 10. Asdepicted in this example, cam 308 may be in first position 366 fortakeoff.

With reference now to FIG. 12, an illustration of a side view ofaircraft 200 with tail skid assembly 220 in contact with surface 1000 isdepicted in accordance with an illustrative embodiment. In thisillustrative example, aircraft 200 may be rotated about pitch axis 224in FIG. 2 for landing on surface 1000. When landing on surface 1000,tail skid assembly 220 may come into contact with surface 1000 tosubstantially prevent tail section 212 of aircraft 200 from contactingsurface 1000.

With reference now to FIG. 13, an illustration of an enlarged side viewof tail skid assembly 220 in contact with surface 1000 is depicted inaccordance with an illustrative embodiment. In FIG. 13, an enlarged sideview of tail skid assembly 220 in contact with surface 1000 duringlanding in FIG. 12 may be depicted taken with respect to lines 13-13 inFIG. 12. As depicted in this example, cam 308 may be in second position400 for landing.

In this illustrative example, clearance 1300 may be the additionalground clearance between surface 1000 and structure 301 that may beprovided by tail skid assembly 220 when cam 308 is in first position366, such as first position 366 for cam 308 in FIG. 11. As depicted,second position 400 of cam 308 may provide less clearance betweensurface 1000 and structure 301 during landing as compared to firstposition 366 of cam 308 during takeoff.

In other words, using tail skid assembly 220, aircraft 200 in FIG. 2 mayhave a greater maximum rotation angle during landing as compared totakeoff. This additional amount of rotation may allow aircraft 200 toreduce a speed of aircraft 200 during landing to a desired level.

With reference now to FIG. 14, an illustration of a process forpositioning a tail skid assembly for a maximum rotation angle for anaircraft in the form of a flowchart is depicted in accordance with anillustrative embodiment. The process illustrated in FIG. 14 may beimplemented using tail skid assembly 106 having cam 118 in FIG. 1.

The process may begin by determining whether tail skid assembly 106 isto be deployed for takeoff 110 or landing 112 (operation 1400). If thetail skid assembly 106 is to be deployed for takeoff 110, the processidentifies a set of parameters for takeoff 110 (operation 1402). Inoperation 1402, the set of parameters for takeoff 110 may include atleast one of a takeoff field length, a length of the aircraft, a weightof the aircraft, a thrust generated by an engine system of the aircraft,a takeoff speed, a ground clearance requirement, safety requirements,and other suitable parameters for takeoff 110.

Thereafter, the process may identify a desired maximum rotation anglefor aircraft 100 for takeoff 110 using the set of parameters identified(operation 1404). The desired maximum rotation angle for takeoff 110 maybe first maximum rotation angle 164.

The process may then deploy tail skid assembly 106 in a manner thatallows the desired maximum rotation angle for aircraft 100 duringtakeoff 110 (operation 1406), with the process terminating thereafter.In operation 1406, deploying tail skid assembly 106 to provide firstmaximum rotation angle 164 for aircraft 100 includes moving deploymentdevice 119 in tail skid assembly 106 to first position 160.

With deployment device 119 in first position 160, elongate structure 113in tail skid assembly 106 may have a first deployed position. The firstdeployed position for elongate structure 113 may provide a distancebetween second end 128 of elongate structure 113 and a bottom of tailsection 104 of aircraft 100 that allows first maximum rotation angle164.

With reference again to operation 1400, if tail skid assembly 106 is tobe deployed for landing 112, the process identifies a set of parametersfor landing 112 (operation 1408). In operation 1408, the set ofparameters for landing 112 may include at least one of a landing fieldlength, a length of the aircraft, a weight of the aircraft, a thrustgenerated by an engine system of the aircraft, a landing speed, a groundclearance requirement, safety requirements, and other suitableparameters for landing 112.

Thereafter, the process may identify a desired maximum rotation anglefor aircraft 100 for landing 112 using the set of parameters identified(operation 1410). The desired maximum rotation angle for landing 112 maybe second maximum rotation angle 166. Second maximum rotation angle 166may be greater than first maximum rotation angle 164.

The process may then deploy tail skid assembly 106 in a manner thatallows the desired maximum rotation angle for aircraft 100 duringlanding 112 (operation 1412), with the process terminating thereafter.In operation 1412, deploying tail skid assembly 106 to provide secondmaximum rotation angle 166 for aircraft 100 includes moving deploymentdevice 119 in tail skid assembly 106 to second position 162.

With deployment device 119 in second position 162, elongate structure113 in tail skid assembly 106 may have a second deployed position. Thesecond deployed position for elongate structure 113 may provide adistance between second end 128 of elongate structure 113 and a bottomof tail section 104 of aircraft 100 that allows second maximum rotationangle 166.

When elongate structure 113 has the first deployed position, thedistance between second end 128 of elongate structure 113 and a bottomof tail section 104 of aircraft 100 is greater than when elongatestructure 113 has the second deployed position. In this manner, agreater ground clearance is provided for aircraft 100 during takeoff 110as compared to landing 112.

The flowchart and block diagrams in the different depicted embodimentsillustrate the architecture, functionality, and operation of somepossible implementations of apparatuses and methods in an illustrativeembodiment. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment, function, and/or a portion ofan operation or step. For example, one or more of the blocks may beimplemented as program code, in hardware, or a combination of theprogram code and hardware. When implemented in hardware, the hardwaremay, for example, without limitation, take the form of integratedcircuits that are manufactured or configured to perform one or moreoperations in the flowchart or block diagrams.

In some alternative implementations of an illustrative embodiment, thefunction or functions noted in the blocks may occur out of the ordernoted in the figures. For example, in some cases, two blocks shown insuccession may be executed substantially concurrently, or the blocks maysometimes be performed in the reverse order, depending upon thefunctionality involved. Also, other blocks may be added in addition tothe illustrated blocks in a flowchart or block diagram.

Illustrative embodiments of the disclosure may be described in thecontext of aircraft manufacturing and service method 1500 as shown inFIG. 15 and aircraft 1600 as shown in FIG. 16. Turning first to FIG. 15,an illustration of an aircraft manufacturing and service method isdepicted in accordance with an illustrative embodiment. Duringpre-production, aircraft manufacturing and service method 1500 mayinclude specification and design 1502 of aircraft 1600 in FIG. 16 andmaterial procurement 1504.

During production, component and subassembly manufacturing 1506 andsystem integration 1508 of aircraft 1600 may take place. Thereafter,aircraft 1600 may go through certification and delivery 1510 in order tobe placed in service 1512. While in service 1512 by a customer, aircraft1600 may be scheduled for routine maintenance and service 1514, whichmay include modification, reconfiguration, refurbishment, and othermaintenance or service.

Each of the processes of aircraft manufacturing and service method 1500may be performed or carried out by a system integrator, a third party,and/or an operator. In these examples, the operator may be a customer.For the purposes of this description, a system integrator may include,without limitation, any number of aircraft manufacturers andmajor-system subcontractors; a third party may include, withoutlimitation, any number of vendors, subcontractors, and suppliers; and anoperator may be an airline, a leasing company, a military entity, aservice organization, and so on.

With reference now to FIG. 16, an illustration of an aircraft isdepicted in which an illustrative embodiment may be implemented. In thisexample, aircraft 1600 is produced by aircraft manufacturing and servicemethod 1500 in FIG. 15 and may include airframe 1602 with plurality ofsystems 1604 and interior 1606.

Examples of systems 1604 may include one or more of propulsion system1608, electrical system 1610, hydraulic system 1612, environmentalsystem 1614, and tail section protection system 1616. Tail sectionprotection system 1616 may include tail skid assembly 1618. Tail skidassembly 1618 may be implemented using, for example, without limitation,tail skid assembly 106 in FIG. 1. Any number of other systems may beincluded. Although an aerospace example is shown, different illustrativeembodiments may be applied to other industries, such as the automotiveindustry.

Apparatuses and methods embodied herein may be employed during at leastone of the stages of aircraft manufacturing and service method 1500 inFIG. 15. For example, without limitation, cam 118 in FIG. 1 may be addedto tail skid assembly 1618 in aircraft 1600 to allow tail skid assembly1618 to provide different maximum rotation angles for aircraft 1600during different phases of flight.

For example, without limitation, cam 118 in FIG. 1 may be designed foruse in tail skid assembly 1618 in aircraft 1600 during at least one ofspecification and design 1502 and routine maintenance and service 1514.Further, cam 118 in FIG. 1 may be added to tail skid assembly 1618 foraircraft 1600 during at least one of production, component andsubassembly manufacturing 1506, system integration 1508, maintenance andservice 1514, and some other suitable stage during aircraftmanufacturing and service method 1500.

In one illustrative example, components or subassemblies produced incomponent and subassembly manufacturing 1506 in FIG. 15 may befabricated or manufactured in a manner similar to components orsubassemblies produced while aircraft 1600 is in service 1512 in FIG.15. As yet another example, one or more apparatus embodiments, methodembodiments, or a combination thereof may be utilized during productionstages, such as component and subassembly manufacturing 1506 and systemintegration 1508 in FIG. 15.

One or more apparatus embodiments, method embodiments, or a combinationthereof may be utilized while aircraft 1600 is in service 1512 and/orduring maintenance and service 1514 in FIG. 15. The use of a number ofthe different illustrative embodiments may substantially expedite theassembly of and/or reduce the cost of aircraft 1600.

Thus, the different illustrative embodiments provide a method andapparatus for changing a deployed position for an elongate structure ina tail skid assembly for an aircraft. In one illustrative example, atail skid assembly may comprise an elongate structure and a deploymentdevice. The elongate structure may be connected to a tail section of anaircraft. The deployment device may be connected to the elongatestructure. The deployment device may be configured to move such that adeployed position for the elongate structure changes to one of aplurality of deployed positions for the elongate structure.

The description of the different illustrative embodiments has beenpresented for purposes of illustration and description and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different illustrativeembodiments may provide different features as compared to otherillustrative embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A tail skid assembly comprising: an elongatestructure connected to a tail section of an aircraft; and a deploymentdevice connected to the elongate structure, such that the elongatestructure occupies one of a plurality of deployed positions; and anactuator system connected: at a first end of the actuator system to theaircraft at an axis connecting a first end of the elongate structure tothe aircraft, and at a second end of the actuator system to a pinconnected to: the deployment device connected to an energy absorbingdevice, and an elongate opening in the elongate structure.
 2. The tailskid assembly of claim 1, wherein the deployment device is configured torotate between a first position relative to the elongate structure and asecond position relative to the elongate structure such that theelongate structure has a first deployed position in the plurality ofdeployed positions when the deployment device is in the first positionand the elongate structure has a second deployed position in theplurality of deployed positions when the deployment device is in thesecond position.
 3. The tail skid assembly of claim 2, wherein theelongate structure further comprises a contact member associated with asecond end of the elongate structure, the contact member configured tocome into contact with a surface and being a first distance from thetail section of the aircraft with the elongate structure in the firstdeployed position, and a second distance from the tail section of theaircraft with the elongate structure in the second deployed position. 4.The tail skid assembly of claim 3, wherein the elongate structure hasthe first deployed position during takeoff and the elongate structurehas the second deployed position during landing and wherein the firstdistance between the contact member and the tail section of the aircraftduring takeoff is greater than the second distance between the contactmember and the tail section of the aircraft during landing.
 5. The tailskid assembly of claim 2, wherein the elongate structure in the firstdeployed position allows a first maximum rotation angle for the aircraftand wherein the elongate structure in the second deployed positionallows a second maximum rotation angle for the aircraft.
 6. The tailskid assembly of claim 5, wherein the elongate structure has the firstdeployed position during takeoff and the second deployed position duringlanding and wherein the second maximum rotation angle is greater thanthe first maximum rotation angle.
 7. The tail skid assembly of claim 1further comprising: the actuator system configured to move thedeployment device such that the deployment device rotates, whereinrotation of the deployment device changes the deployed position for theelongate structure.
 8. The tail skid assembly of claim 7 furthercomprising: the pin connecting the deployment device to the elongatestructure being inserted through an opening in the deployment device andan elongate opening in the elongate structure; and the actuator systemis configured to move the pin in the elongate opening such that thedeployment device moves.
 9. The tail skid assembly of claim 7 furthercomprising: a reaction link connected to the actuator system and to thedeployment device in which the reaction link creates a moment when theactuator system moves the deployment device and in which the momentcauses the deployment device to rotate.
 10. The tail skid assembly ofclaim 7, wherein the actuator system comprises at least one of ahydraulic actuator, a linear actuator, and a pneumatic actuator.
 11. Thetail skid assembly of claim 1, wherein the deployment device has aneccentric geometry in which a first length of the deployment device isdifferent from a second length of the deployment device.
 12. The tailskid assembly of claim 1, wherein the elongate structure is a lever andthe deployment device is a cam.
 13. The tail skid assembly of claim 1further comprising: the energy absorbing device connected to the tailsection of the aircraft, the deployment device being connected to theenergy absorbing device such that the deployment device rotates about anaxis through a connection between the energy absorbing device and thedeployment device.
 14. The tail skid assembly of claim 13, wherein theconnection between the deployment device and the energy absorbing devicecomprises at least one: of a fastener, a pin, an opening, and a hinge.15. The tail skid assembly of claim 1, wherein movement of thedeployment device changes the deployed position for the elongatestructure to change a maximum rotation angle for the aircraft in whichthe maximum rotation angle for the aircraft is a maximum angle at whichthe aircraft can rotate about a pitch axis before the tail skid assemblycontacts a surface during at least one of takeoff and landing.
 16. Atail skid assembly comprising: an elongate structure having a first endand a second end in which the first end is connected to a tail sectionof an aircraft; and a deployment device connected to: an energyabsorbing device, a reaction link, and an actuator system, and theelongate structure via a pin that connects the actuator system to thedeployment device, and moves the deployment device such that a distancebetween the second end of the elongate structure and a bottom of thetail section of the aircraft becomes one of a plurality of selecteddistances.
 17. The tail skid of claim 16, further comprising thereaction link configured to connect to the actuator system.
 18. The tailskid of claim 16, further comprising a second pin configured to connectthe actuator system and the elongate structure to the tail section ofthe aircraft.
 19. The tail skid of claim 16, further comprising: thedeployment device configured to rotate about: an end of the energyabsorbing device, an end of the reaction link; and, the first end of theelongate structure and an end of the actuator system each rotatablyconnected to the tail section about an axis.
 20. An apparatus configuredto deploy a tail skid a distance from a body of an aerial vehicle, theapparatus comprising: a deployment device comprising: eccentricgeometry, a first opening, a second opening, and a third opening; anenergy absorbing device rotatably connected to the deployment device viaa first pin through the first opening; a reaction link rotatablyconnected, at a first end of the reaction link, to the deployment devicevia a second pin through the second opening, and rotatably connected, ata second end of the reaction link, to an actuator system; the actuatorsystem rotatably connected at a first end of the actuator system, to thedeployment device via a third pin through the third opening, such thatthe third pin engages in an elongate opening in an elongate structure;and the elongate structure connected: at a first end of the elongatestructure to the vehicle via a fourth pin that connects a second end ofthe actuator system to the vehicle, and at a second end of the elongatestructure to the tail skid.